INT 7A - Novell NetWare - IPX Driver - LISTEN FOR PACKET

	BX = 0004h
	ES:SI -> Event Control Block (see BX=0003h)
Return: AL = status
	    00h successful
	    FFh no listening socket for packet
Desc:	this function provides IPX with an ECB for receiving an IPX packet, but
	  does not wait for a packet to arrive
Notes:	the application must open a socket and initialize the ECB's ESR
	  address, socket number, fragment count, and fragment descriptor
	  fields before invoking this function
	there is no limit on the number of ECBs which may simultaneously be
	  listening on a socket
	this function is supported by Advanced NetWare 1.02+
SeeAlso: BX=0000h,BX=0003h